Well... for those in the US, I have a new sealed unit from US SonyStyle store for sale. My brother ordered me one as a b-day gift, but I'm pretty satisfied with my X5 at the moment. I'm not going to post the link here, but if you are interested you can find it in for sale section or through my profile.

I received this new Sony ZX-2 player as a b-day gift from my brother. Being that I'm pretty satisfied with my X5 at the moment, I'm posting this new sealed player for sale. This is a sealed US player that was directly purchased from SonyStyle
I will cover Priority shipping and full insurance within US but buyer will take care of PayPal fees. NO TRADES!
This sale is for US only as I'm not comfortable shipping something of this value overseas.
Of course, if you...

I'm the second owner of these Alpha Dogs, and besides a small blemish on the left ear cup that is not very visible, they are in good shape.
They are the later version with the BMF tuning dots and tuning pads.
Buyer splits shipping if within CONUS and please send Paypal gift (or buyer takes care of fees)
- Price is firm and NO TRADES-

These are in like new condition.
They are the latest version with Brown headband, which has a bit more padding than the black headband, also looks much classier.
Price is FIRM and buyer pays for actual shipping and fees if gift is not used.
NO TRADES

Depends on what your usage will be. Have never tried DigiZoid so I don't know much about its performance, but for Arrow 5, you might want to check out the 5N instead if your main use is with full size. If my memory serve me correctly, the 5P's bass boost is very much like the 3G's, which has 9db boost on level 1 and +18db for level 2. When using the bass boost with my IEM, level 1 works pretty well and adds a deep punch, but level 2 can be over powering. Level 2 sound...

I think he said the 5P (which is what I have) is a little higher than the other two due to the higher gain. I'm not sure if it's only exist/evident with the bad boost on, because with no bass boost, the amp was dead silent with the in ear, and just pure blackness with my full size.

I gave it a quick check with my Klipsch X10 in ear to listen for the hiss. Setting volume to max with no music playing, the background is pitch black on gain setting 0 and 1, while 2 has a very faint hiss in the background, again this is with the volume on the absolute max on all three gain settings. I haven't had the chance to try it with the Nexus 5, but is was noticeably better than my ONE M7.